package utils

import (
  "io/ioutil"
  "os"
  "strconv"
)

// 前端传来文件片与当前片为什么文件的第几片
// 后端拿到以后比较次分片是否上传 或者是否为不完全片
// 前端发送每片多大
// 前端告知是否为最后一片且是否完成

const breakpointDir = "./breakpointDir/"
const finishDir = "./fileDir/"

//@author: [piexlmax](https://github.com/piexlmax)
//@function: BreakPointContinue
//@description: 断点续传
//@param: content []byte, fileName string, contentNumber int, contentTotal int, fileMd5 string
//@return: error, string

func BreakPointContinue(content []byte, fileName string, contentNumber int, contentTotal int, fileMd5 string) (error, string) {
  path := breakpointDir + fileMd5 + "/"
  err := os.MkdirAll(path, os.ModePerm)
  if err != nil {
    return err, path
  }
  err, pathc := makeFileContent(content, fileName, path, contentNumber)
  return err, pathc

}

//@author: [piexlmax](https://github.com/piexlmax)
//@function: CheckMd5
//@description: 检查Md5
//@param: content []byte, chunkMd5 string
//@return: CanUpload bool

func CheckMd5(content []byte, chunkMd5 string) (CanUpload bool) {
  fileMd5 := MD5V(content)
  if fileMd5 == chunkMd5 {
    return true // 可以继续上传
  } else {
    return false // 切片不完整，废弃
  }
}

//@author: [piexlmax](https://github.com/piexlmax)
//@function: makeFileContent
//@description: 创建切片内容
//@param: content []byte, fileName string, FileDir string, contentNumber int
//@return: error, string

func makeFileContent(content []byte, fileName string, FileDir string, contentNumber int) (error, string) {
  path := FileDir + fileName + "_" + strconv.Itoa(contentNumber)
  f, err := os.Create(path)
  if err != nil {
    return err, path
  } else {
    _, err = f.Write(content)
    if err != nil {
      return err, path
    }
  }
  defer f.Close()
  return nil, path
}

//@author: [piexlmax](https://github.com/piexlmax)
//@function: makeFileContent
//@description: 创建切片文件
//@param: fileName string, FileMd5 string
//@return: error, string

func MakeFile(fileName string, FileMd5 string) (error, string) {
  rd, err := ioutil.ReadDir(breakpointDir + FileMd5)
  if err != nil {
    return err, finishDir + fileName
  }
  _ = os.MkdirAll(finishDir, os.ModePerm)
  fd, err := os.OpenFile(finishDir+fileName, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0644)
  if err != nil {
    return err, finishDir + fileName
  }
  defer fd.Close()
  for k := range rd {
    content, _ := ioutil.ReadFile(breakpointDir + FileMd5 + "/" + fileName + "_" + strconv.Itoa(k))
    _, err = fd.Write(content)
    if err != nil {
      _ = os.Remove(finishDir + fileName)
      return err, finishDir + fileName
    }
  }
  return nil, finishDir + fileName
}

//@author: [piexlmax](https://github.com/piexlmax)
//@function: RemoveChunk
//@description: 移除切片
//@param: FileMd5 string
//@return: error

func RemoveChunk(FileMd5 string) error {
  err := os.RemoveAll(breakpointDir + FileMd5)
  return err
}
